Significance of the system
It is important that blood glucose levels are maintained within fairly strict limits, between 4-8mmol/L, as the cells in the brain and central nervous system cannot make glucose or store more than a few minutes supply. They need a constant supply to function properly and carry out essential life processes such as respiration. Also, it is furthermore important because some tissues cannot use fats or amino acids to produce ATP; these almost exclusively rely on glucose to produce ATP and cannot use anything else.
Why does blood glucose need to be maintained?
Blood glucose needs to maintained within fairly strict limits because problems will result if those levels get too low below 4mmol/L (hypoglycaemia), or too high above 13 mmol/L (hyperglycaemia).
How are blood glucose levels maintained
In a healthy person, blood glucose levels are restored to normal levels primarily through the actions of two pancreatic hormones, insulin and glucagon. These are negative feedback systems and are coordinated by the brain, and specifically, the hypothalamus.
How does the system respond to an increase in blood glucose levels?
If blood glucose levels rise after eating, the beta cells (receptors) in the pancreas respond by secreting insulin (effector). Insulin first travels to the liver through the portal vein, and provide a feedback signal that tells the liver to stop releasing glucose into the blood stream (shuts down hepatic glucose production). It instead tells it to start storing glucose as glycogen. Insulin then travels to the rest of the tissues in the body through the blood stream, and signals to muscle and fats cells to tell them to also take up glucose and store it as glycogen or fat.
Why does blood glucose homeostasis advantage us?
In normal humans, having internal systems that manage and maintain blood glucose levels is a huge adaptive advantage, as it means that we have flexibility around when we eat, as we do not have to eat as regularly. If we did not have these internal systems, we would not have the ability to store glucose in the form of glycogen, which could later be used by cells as energy for life processes. We would have to be constantly eating glucose rich foods to supply our body with enough glucose to supply cells with energy in the form of ATP for essential life processes such as respiration. We would also be at constant risk of hyperglycemia and hypoglycemia, which can pose serious health risks. Without Alpha and Beta cells in the pancreas releasing glucagon and insulin to maintain blood glucose levels, we would have to control and try to maintain our blood glucose through our diet, which would be extremely challenging and ineffective.
Homeostasis and Glucose Regulation.
Your job is to report on how the human body regulates blood glucose levels.
Define homeostasis
Describe the normal functioning system first, in detail sufficient to explain it to a year 13 HPE class.
Investigate Type 2 Diabetes and how the normal functioning of the homeostatic feedback mechanism breaks down.
Resource Links
http://scienceisntfiction.blogspot.co.nz/2011/04/negative-feedback-and-blood-glucose.html
http://www.biologyreference.com/Bl-Ce/Blood-Sugar-Regulation.htm
http://www.medicalnewstoday.com/info/diabetes/type1diabetes.php
The prezi is too hard to read, but the transcript has some useful points.
Transcript from https://prezi.com/bg1yism53c9f/blood-glucose-homeostasis/.
Significance of the system
It is important that blood glucose levels are maintained within fairly strict limits, between 4-8mmol/L, as the cells in the brain and central nervous system cannot make glucose or store more than a few minutes supply. They need a constant supply to function properly and carry out essential life processes such as respiration. Also, it is furthermore important because some tissues cannot use fats or amino acids to produce ATP; these almost exclusively rely on glucose to produce ATP and cannot use anything else.
Why does blood glucose need to be maintained?
Blood glucose needs to maintained within fairly strict limits because problems will result if those levels get too low below 4mmol/L (hypoglycaemia), or too high above 13 mmol/L (hyperglycaemia).
How are blood glucose levels maintained
In a healthy person, blood glucose levels are restored to normal levels primarily through the actions of two pancreatic hormones, insulin and glucagon. These are negative feedback systems and are coordinated by the brain, and specifically, the hypothalamus.
How does the system respond to an increase in blood glucose levels?
If blood glucose levels rise after eating, the beta cells (receptors) in the pancreas respond by secreting insulin (effector). Insulin first travels to the liver through the portal vein, and provide a feedback signal that tells the liver to stop releasing glucose into the blood stream (shuts down hepatic glucose production). It instead tells it to start storing glucose as glycogen. Insulin then travels to the rest of the tissues in the body through the blood stream, and signals to muscle and fats cells to tell them to also take up glucose and store it as glycogen or fat.
Why does blood glucose homeostasis advantage us?
In normal humans, having internal systems that manage and maintain blood glucose levels is a huge adaptive advantage, as it means that we have flexibility around when we eat, as we do not have to eat as regularly. If we did not have these internal systems, we would not have the ability to store glucose in the form of glycogen, which could later be used by cells as energy for life processes. We would have to be constantly eating glucose rich foods to supply our body with enough glucose to supply cells with energy in the form of ATP for essential life processes such as respiration. We would also be at constant risk of hyperglycemia and hypoglycemia, which can pose serious health risks. Without Alpha and Beta cells in the pancreas releasing glucagon and insulin to maintain blood glucose levels, we would have to control and try to maintain our blood glucose through our diet, which would be extremely challenging and ineffective.
Cell membrane structure and the glucose transport mechanism is very important. How the insulin actually changes the cell membrane, without entering the cell itself, is pretty easy to explain.
Link to video of the cell membrane structure
https://unlockinglifescode.org/media/animations/515?page=1#504
and to explain the transport across the membrane
https://www.youtube.com/watch?v=OlHez8gwMgw
and the whole show in detail at the Khan Academy
https://www.youtube.com/watch?v=Id2E72P8Fe0